A year or two ago I read an article that said that scientists at last had a theory about why humans, although mostly hairless, still have little hairs on their bodies. Why didn't our ancestors lose all their hair?
I had thought I knew the answer to this and that the answer was obvious. If you had asked me, I would have said: the little hairs are to make you more sensitive to insects. You have these sensors in your skin, which can detect mechanical pressure. How can we make them more sensitive? Attach a little lever to each one. Now if anything bumps the lever, the magnified force will be transmitted to the sensor.
So when I saw that there was an article about this, I expected it was going to say something like this: “Scientists formerly assumed that the evolutionary function of the hairs was to increase sensitivity of the mechanoreceptors in the skin. But actually, it turns out to be something else entirely…”
Nope, I read the article, and it was about these scientists earnestly explaining that the hairs function to increase sensitivity of the mechanoreceptors in the skin.
Maybe the person writing the article missed some important nuance, something like “yes, scientists have long supposed that the hairs were to increase sensitivity, but we now have the first real confirmation of that theory”. I don't know.
When I do Google search for “why do arms have little hairs” I get a lot of answers that claim it's to help keep us warm. Hahahaha. Bullshit.
(Why do we still have thick bushy hair on the tops of our heads? Dominus says: to prevent sunburn. I read something recently about why we have brow ridges and eyebrows; the claim was that it increases the expressiveness of facial communication. Maybe, but Dominus says: they are primarily to help prevent sweat from dripping into your eyes. Why do men go bald as they age, but only on their heads? Dominus says: I have no idea.)